This invention relates to the control of the quality of drinking water, and particularly to a mechanism for monitoring the water quality to prevent the use of water that is not being adequately treated until corrective measures have been taken.
In certain geographical areas the water supply contains levels of radioactivity in excess of the limits established by primary drinking water regulations. The source of this radioactivity is naturally occuring and is found where the water supply is obtained from deep wells in an acquifer that contains radioactive rock. Levels of radioactivity are very low, but a value of twice the current limit established by the regulations is not uncommon. The sources of the radioactivity in the water are metallic ions that are easily removed from the water by the common ion exchange process used to soften water.
Although the solution to the removal of the radioactivity is quite simple since a common water softener can be used, such softeners require periodic regeneration because they lose their effectiveness as the ion exchange material becomes completely or nearly completely saturated with the removed ions. Thus, some mechanisms must be provided to insure that the softeners are being regenerated periodically and that the softening process is operating to remove the radioactivity. At the same time, the mechanism should, preferably, prevent the consumption of inadequately treated water.
One aspect of the invention involves a water quality monitor that includes a sensor that is exposed to the treated water leaving the water softener. The sensor responds to the change in the quality of the water leaving the softener. When the ion exchange resin of the softener becomes exhausted to a predetermined degree, the sensor will actuate signaling means that indicates to the user that the water quality has deteriorated to an unacceptable level and that corrective action should be taken. The sensor continues to actuate the signaling means until the spent sensor is replaced with a fresh sensor. The signaling means can provide a visual or audible signal or actuate a valve in the service line leading from the softener so that the flow of water at a point of usage will be restricted or entirely halted. The sensor preferably includes a small quantity, or sample of an ion exchange resin that changes volume significantly as it absorbs calcium ions.